The present invention relates generally to a remotely controlled cutter apparatus for use within a conduit or pipe, and more particularly, to a remotely controlled cutter for use in re-establishing lateral connections in a previously lined sewer pipe or conduit.
It is generally well known that conduits or pipes which are employed for conducting fluids such as sanitary sewer pipes, storm sewer pipes, water lines, and gas lines, frequently require repair due to leakage. The leakage may be inwardly, from the environment into the pipe, or outwardly, from the pipe into the environment. The leakage may be due to improper formation or installation of the conduit or pipe, deterioration of the conduit or pipe due to ageing, attacks by acid or other corrosive materials, cracking due to earthquakes or vibrations caused by vehicular traffic, improper care, or a variety of other causes. Regardless of the cause, such leakage is undesirable because it may result in waste of the fluid being carried by the pipe, damage to the environment, and the possible creation of public health hazards.
Because of ever increasing labor and machinery cost, it is becoming increasingly more expensive to dig up and replace the leaking pipes or conduits. Additionally, it has become increasingly unacceptable and impractical to dig up the leaking pipes or conduits and physically replace them with new pipes due to the amount of space required by construction equipment and personnel, as well as the disruption to normal traffic patterns within a municipality.
As a result, various methods have been devised for the in situ repair or rehabilitation of existing pipes, thereby avoiding the expense, hazard, and inconvenience involved in digging up and replacing the leaking or damaged pipes. Some of these methods involve the insertion of an elongated flexible tubular liner comprised of felt or similar material that has been impregnated with a thermal setting synthetic resin into a deteriorated pipe. The liner is ultimately expanded and shaped to match the inner diameter of the pipe to be lined and the resin is allowed to cure to form a relatively hard, tight fitting, rigid pipe lining within the pipe. This liner effectively seals any cracks in the pipe and repairs any pipe or joint deterioration, thereby preventing further leakage either into or out of the pipe.
Another in situ repair technique involves the use of a folded polyethylene pipe in which a polyethylene pipe is generally folded into a U-shape cross-section and inserted into the damaged pipe. Thereafter, the U-shaped liner is expanded through use of temperature and pressure until it conforms with the shape of the inside surface of the original pipe wall.
Typically, the main conduit for a sanitary sewer system will have a plurality of connecting service entrances, or laterals, which carry sewage from individual sources into the main pipe. As is readily apparent, when the damaged pipe or conduit has been relined, all of the service entrances or laterals are effectively covered and sealed by the liner. Therefore, it is necessary to re-establish, or re-open, these lateral connections with the main sewer pipe. This can be accomplished by either digging up the earth adjacent the lateral connections and cutting holes in the liner corresponding to the lateral connection, or through use of a remotely controlled robotic cutter that is positioned within the lined main sewer pipe and may be operated so as to re-open or re-establish the openings from within the lined pipe.
Unlike prior art robotic cutters, the robotic cutter described herein enables a cutting tool to be rotated in a true circular arc about the longitudinal axis of the lateral pipe, thus ensuring that the opening for a lateral connection is a true circle. With prior art robotic cutters, the cutting tool cannot be rotated in a true circular path; rather, cutouts had to be made by manually controlling the longitudinal, vertical and/or rotational movement of the cutter head assembly. The prior art techniques require a very skilled cutter operator, are very time-consuming, and results in an inferior opening due to the erratic nature of the cut. Moreover, since the prior art robotic cutters cannot make a true circular cut, the openings made by such cutters is not uniform and frequently fail to fully open the lateral connection, thereby increasing the chances of subsequent blockage of the lateral openings.